Study Of High-Dimensional Mapping Technology Based On Erroneous Bits Minimization

Recent years have seen a rapid development of communication technologies and their bandwidth consumption businesses such as high-definition videos,sports broadcasting,cloud sharing,on-line games and video conferences.As a result,the demand for capacity in core networks is growing at an alarming rate of 160% every year.At the same time,with the continuous promotion of intelligent life which is guided by big data and web of things,the needs for bandwidth is bound to exceed any stage of history.How to extend the capacity with little increase in arterial reconstruction costs is one of the major problems facing the current optical fiber communication systems.Utilizing high-order modulation formats is one of the effective means of capacity enlargement.However,the spectral efficiency and the power efficiency is a pair of contradiction.For higher order modulation formats,though the spectrum efficiency is high,but the power efficiency is reduced.Under the same transmission power and target bit error rate,smaller power efficiency will result in a shorter transmission distance.To solve this problem,efforts have been made to improve the performance of coherent optical systems by considering joint modulation of multiple degrees of freedom in the electromagnetic field,which results in a kind of novel modulation formats called high-dimensional modulation formats.By encoding data simultaneously into several frequency bands,modes,time slots and polarizations,high-dimensional modulation formats can improve the power efficiency by maximizing the minimum Euclidean distance between constellation points,which solves the problem that the spectral efficiency and the power efficiency are mutually restricted in the two-dimensional modulation scheme,and makes the realization of long-distance optical fiber communication system is possible.High-dimensional modulation formats can make use of the current communication transmission networks.By converting modulation formats at the transmitter and utilizing digital signal processing at the receiver,high-dimensional modulation formats can improve the system performance without changing the structure of optical communication systems.Therefore,the study of high-dimensional modulation format is of great significance.Motivated by this,this paper has studied and explored one of the four key technologies of high-dimensional mapping technology,and put forward a new solution based on “erroneous bits minimization”.The main works of this paper are as follows:Firstly,we made a detailed elaboration of the great significance of high-dimensional modulation formats for the development of communication technologies.According to the developing history and current situation,We summarized the research results both home and abroad systematically.Then,we explained the basic concepts and major parameters of highdimensional modulation formats,especially for asymptotic power efficiency and spectral efficiency.Straight after that,we introduced three implementation methods of this kind of modulation formats from two aspects,principle and step.Then we illustrated three high-dimensional modulation formats widely studied nowadays according to their implementation principles,transmission performances and hardware implementations.Secondly,based on the research status of high-dimensional modulation formats in recent years,we discussed the four key technologies of high-dimensional modulation formats.They are constellation points selecting technology,mapping technology,demodulating technology and equalizing technology.Then we analyzed the solutions for each technology with an objective way.Again,based on the analysis above,we put forward a new mapping solution named “erroneous-bits-minimization” high-dimensional mapping.The process of theoretical model establishing was introduced in detail.Then we deduced the upper and lower bound of the single-symbol cost function,and gave a single-symbol cost function curve according to the calculation.At last,we presented the general steps of Erroneous-Bits-Minimization high-dimensional mapping.These works have provided a solid theoretical basis for the application of this mapping technology.Finally,we built a high-dimensional simulation system utilizing VPI-MATLAB joint simulation platform.The performance of the proposed erroneous-bitsminimization high-dimensional mapping was simulated and validated by comparing with random mapping.The mapping gain and BER performance of six four-dimensional modulation formats and six eight-dimensional modulation formats were analyzed systematically.The simulation results showed good consistency of the mapping gain and the error performance,fully demonstrating the correctness of the “erroneous-bits-minimization” theoretical model and the good performance of the proposed method of high-dimensional mapping.